The appearance of an object is a visual sensation caused by the light radiated from the object under study. The appearance is essentially a combination of features in a spatial domain and a tri-chromatic domain. Objects in general have a principally different appearance in different angular orientations, relative to the incident light source (electromagnetic radiator) and the observer (receptor). Common imaging devices, e.g. digital cameras and computer scanners resolve the spatial domain and usually the tri-chromatic domain. To also describe the angular dependent behavior, it is necessary to also include the angular degree of freedom in the characterization process. Capturing and characterizing a spatial, angular and tri-chromatic optical response of an object, forms a powerful basis when characterizing the objective causes for the appearance of an object.
One, of a number of technical challenges in this context, is that the angle resolved optical characterization of an object often involves a wide range of signal intensities (signal dynamics), including high intensity specular reflections and low intensity reflections from other orientations. Common units for image registration lack the ability to handle the high dynamic range of intensities normally present in the context and are therefore not suited for the task.
Characterizing the objective causes for the appearance of an object is of high industrial relevance e.g. when conducting product development within the paper industry. The product development may deal reducing certain deficiencies in a certain characteristic of the product, say undesired gloss variation. A characterization of the objective causes for the appearance of the product, including the undesired gloss variation, would be a vital help in the search of countermeasures to reduce the unwanted behavior. The characterization of the objective causes of the appearance of an object would increase the efficiency of product development efforts.
Known methods for characterizing the objective causes for the appearance of a product are not effective enough because the data gathered by these methods does not allow for an efficient characterization of high dynamic range spectrally, spatially and angularly resolved radiation data. As each and every of these characteristic features of the resulting information volume are vital, every characterization method that lacks at least one of these features will be a suboptimal characterization method. There is therefore a clear and apparent need for an improved method. Present invention meets this need. The present invention yields new relevant information that facilitates finding solutions to previously unsolvable problems. Alleviating problems associated with the characterization of data will contribute to more efficient product development efforts and finally in better and cheaper end products.